Grain carts are typically used to transport harvested grain from the field to a truck waiting alongside the field. An empty grain cart pulls alongside a moving combine and an offload auger conveys the grain in the combine to the hopper of grain cart. When hopper of the grain cart is full, the grain cart pulled by a tractor is moved to alongside the hopper trailer of a truck alongside the edge of the field, typically on a roadside. The typical grain cart will have a discharge conveyor with a two-part auger housing, where the upper auger housing is moveable between a storage position (also sometimes referred to as a field position) and an unload position. While moving the grain cart from the combine to the hopper trailer, the upper auger housing will typically be in the storage position, i.e., disengaged from the lower auger housing and folded in front of the grain cart. Upon reaching the side of the hopper trailer, the tractor operator will move the upper auger housing from the storage position to the unload position such that the lower auger housing and the upper auger housing are aligned to form a continuous auger housing. The discharge end of the upper auger housing will be positioned overtop of the hopper trailer to offload the hopper of the grain cart to the hopper trailer.
The inlet or feed end of the lower auger housing is positioned within the hopper of the grain cart. The inlet end includes a moveable auger feed gate that opens and closes the inlet end. When the auger feed gate is open, grain from the hopper of the grain cart may enter the inlet end and be carried through the continuous auger housing when the auger is rotating. During the offloading process, the grain cart operator may want to shut the auger feed gate to stop the flow of grain through the auger housings, such as when the hopper trailer becomes full. The auger typically continues to rotate while the gate is being closed and/or for a short time period after closing the gate so the discharge conveyor can be cleared of any remaining grain.
It is not uncommon for the operator of the grain cart, however, to inadvertently activate the lever that controls the upper auger housing causing the upper auger housing to start folding toward the storage position and separating from the lower auger housing. Because the auger is still rotating and grain remains in the lower auger housing, grain begins to discharge out of the top of the lower auger housing which is no longer aligned with the now moving and disengaged upper auger housing. When the operator recognizes the mistake, the usual reaction is to quickly reverse the lever to force the upper auger housing back into the unload position. When reversing the direction of the upper auger housing, the stopped upper auger may slam into the rotating lower auger. Consequently, the lower auger, upper auger, upper auger housing, springs, and bearings can sustain enough damage that downtime and repairs will be necessary. This downtime and repairs may significantly slow down or stop the harvesting operation. Moreover, moving the upper auger housing into the unload position while grain is flowing from the top end of the lower auger housing can cause grain to occlude or otherwise block proper engagement of the upper and lower auger housings when the operator performs such a movement back towards the unload position.
The drive line and auger system may also be damaged if the auger is engaged, i.e., commanded to rotate, with the auger feed gate open and the hopper of the grain cart contains a substantial amount of grain. Under these circumstances, the lower auger is exposed to the load pressure of the grain in the hopper which may cause extensive damage to the drive line and auger system. It is best practice to empty the augers by having the auger feed gate closed while running the augers a sufficient time to empty the auger housings. It is also best practice to fold the upper auger housing to a storage position before transport to prevent damage to the upper auger housing and surroundings.
What is needed is a control system to protect the auger system from being damaged during certain operational events of the grain cart. To this end, it would be desirable to prevent accidental movements of the discharge conveyor out of the unload position when the discharge conveyor is full of or transporting grain.